The invention relates to an additive to polyurethane foam which inhibits scorch. Polyurethane slab-stock foam production involves a vigorous exothermic reaction. The prolonged post-reaction heat exposure leads to chemical changes that appear as darkening in the core of the production foam block and is defined as scorch. To suppress unwanted scorch, manufactures add antioxidant blends which have been generally referred to as scorch inhibitors. Scorch inhibitors act through complex sacrificial reactions that reduce the damaging effects of thermally induced darkening. Scorch inhibitors are thus effective at minimizing product loss.
Overview of Polyurethane Scorching
During the manufacture of polyurethane slabstock foam, a vigorous exothermic reaction is observed resulting in interior discoloration.1 It is generally understood to be the result of the polyol and di-isocyante condensation (gel) reaction and the “blow reaction”. 2

Workers have measured heats of reaction corresponding to the component moieties formed in the polyurethane foam matrix: approximately 24 kcal/mol for urethane and 47 kcal/mol for urea, respectively. Visually, a darkened yellow discoloration known as scorch in the core of the production foam block develops resulting from un-dissipated heat. Investigators have shown that complex free radical reactions drive the scorching process. 3 Degradation effects have been indirectly measured showing chain scission and oxidation of polyether polyol formula components. 4 Formulas such as the present invention have been used to reduce chain scission and general chemical alteration of the PUR foam.